And it's perfectly legal.
To recap: The Chicago PMI came out Wednesday at 9:45 a.m., and it was not good. Economists, on average, forecast a level of 52, so it's no wonder the market shouted "look out below." The actual reading of 46.1 not only missed estimates by a wide margin, but also suggested that things are getting worse, not better. (A level below 50 means economic activity is contracting.)

The S&P 500 naturally swooned on the news -- but it did so before the report was made public, as if big pools of smart money knew what was coming. As Bespoke notes, the S&P 500 was almost unchanged at 9:41 a.m. Then the report "leaked" at 9:42, starting the selloff. By the time the PMI was officially released at 9:45 , the S&P had already given up about ten points. Investors shaved off about another ten after the release.

So what gives? As Bespoke explains, this isn't a case of insider selling, at least in the traditional sense. Kingsbury International, the company that compiles the Chicago PMI, has a service where for $200 a month or more subscribers get access to the Chicago PMI data three minutes early.

As Bespoke puts it so well, although there is nothing illegal in this practice, it does provide yet another example of how the market is stacked against the little guy.